Fountain pen



Oct. 7, 1952 M. s. BAKER EIAL FOUNTAIN PEN 2 SHEETSSHEE'I 1 Filed Aug.25, 1948 INVENTORS.

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Oct. 7, 1952 M. s. BAKER EI'AL FOUNTAIN PEN 2 SHEETSSHEET 2 Filed Aug.25, 1948 Patented Oct. 7, 1952 Janesville, Wis., assignorsto- The ParkerPen Company,- J'anesville, Wis, a corporation of- Wisconsin ApplicationAugust-23, 1948, Serial No. 45.776

This invention relates generally to fountain pens: and has todoparticularly with a filling mechanism therefor of the type embodying abreather tube.

An object is to provide a fountain pen having a multiple stroke fillingmeans embodying, anew and improved breather tube. construction.

Another object is" to provide a fountain pen having a multiplestrokefilling" means ofyimprovedconstruction by which the, ink reservoirmay be filled to maximum capacity with a; minimum number of fillingstrokes.

Anotherobject is to provide a fountain pen of the multiple strokefilling'typ having a breather tube soconstructed and arranged. that itfacil-i tates theflow of ink intothe reservoir upon each stroke of thefilling means and thereby contributes to increased eff ciency of thefilling means.

A further object is to provide a fountain pen having a breather tube'ofsuch construction that a relatively small quantity of ink is expelledfrom the pen upon each compression stroke thereby insuring maximumexpulsion of air from the reservoir and consequently a maximum intake ofink upon each suction stroke.

Another object is to provide a fountain pen of the type employingabreather'tube, which pen embodies a new and improved arrangement forventing through the forward end of the breather tube the air space atthe forward end oi the inlr reservoir, thereby to prevent expulsionofink fromthe pen upon an increase in pressure of the air in the inkreservoir or decrease in the pressure of the surrounding atmosphere. I

Another object is to provide multiple stroke filling means having abreather tube which is ventedin its forward portion but which is'soconstructed and arranged that a minimum quantity of air is forcedthrough the vent and back into the reservoir during each compressionstroke in the filling operation thereby insuring that-a maxi-- mumproportion of the air displaced during the compression stroke isexpelled from the pen and a. maximum quantity of inkis drawn into thependuring the suction stroke.

Other objects will appear from the following description taken inconnection with the appended drawings, wherein:

Figure 1 is a bottom plan view of a fountain pen constructed accordancewith the invention with certain of the parts broken away and sectioned;

Fig. 2 is a longitudinal sectibnal view taken through the iorwardportion of the pen of Fig; 1;

S-CIaims. (01-. 120-46) Fig; 3 is an enlarged longitudinal sectionalview taken through the rearward portion of the pen of Fig. 1;.

Fig. 4 is an enlarged transverse sectional view taken along 11-minofFig. 2;

Fig. 5- is an enlarged transverse sectional view taken along line 5'5-of Fig.- 2-;

Fig; 6-'-is an enlarged transverse sectional View taken along line 6-6of Fig. 2;

Fig. 7 is anenlarged transversesectiona-l view taken'along line 7-4 ofFig. 3; and

Fig. 8 isan enlarged, fragmentary view of" a portion of the structure ofFig. 2.

- For the purpose of illustrating the present invention it is disclosedin connection with a fountain pe-n generally similar to that disclosedin the co-pending application of Kenneth Parker and Ivan D. Tefft',Serial No. 45,624, filed- August 23-, 1 94 8; for Fountain Pen, to whichpen the presentihvention'isexcellently well adapted. However, it will beunderstood that the present invention is not limited to the detailsoithefo'un t'ai'npenshown and described herein but is excellentlyadapted for embodiment in fountainpens of other forms; For example, thenovel breather tube arrangement of our invention may be embodied inother types of multiple stroke filling devices and including otherarrangements for eff'ecting displacement of air from the reservoir. Alsoour breather tube arrangement may be employed with other typesoi feedmeans than that disclosed herein although it is especially efiectivewhen combined-with a feed of the general type illustrated. I

Referring now particularlyto- Ffgs. 1 and 2; the pen includes a casingor housing formed by a barrel; ii) and a" forwardly extending hollowshell H which together surround and substantially inclose' the internalmembers of the pen. The shell and b'arre'l'preferably are formed of asuitable knownplastic- The-pen is provided interior- 1y with an inkreservoir I 2, a writing point or nib l3 (the extreme tip of whichprojects from the shell I'll, andafeed means connected between the'inlcreservoir: l2 and the writing nib for feedi-nginl': to the: latter,which feed means preferably includes; an. ink. governor or= overflowcollector [4 for: controlling the feed of ink,- all of which elements.are more fully described hereinafter.

tubular body, which preferably takes the form of an externally threadedbushing or nipple [5, is provided for connecting a majority of the othermembers forming the pen and. for retaining them proper assembledrelationship. The body l5; preferably formed of a suitable plastic,

is provided with a forward bore I 6 and a rearward bore I1, which may besmaller than the forward bore, and is formed with a plurality ofdifferent external diameters providing in efiect a plurality oflongitudinally displaced sections of different diameters adapted toreceive various of the pen members as hereinafter described. Thereservoir I2 is defined by the rearward bore portion I I of the body Iand by an elongate, flexible and resilient sac I3 having its forwardopen end receiving the reduced section I8. The sac I9, together with therearward portion of the body I5 thus defines an ink reservoir ofsubstantial capacity. In forming the sac preferably the forward open endis of somewhat smaller diameter than the remaining portion of the sac sothat such reduced portion is stretched when applied to the section I8and a tight gripping action of the sac on the section I8 is provided.While the sac I9 may be retained on the section [8 merely by itsresilience, preferably it is secured to the section I8 as by fusing itthereto or by a known cement.

The sac I9 is formed of suitable material of sufficient resilience toremain in expanded condition except when forcibly compressed. Thematerial is resistant to inks of the types commonly used, that is, bothacid and alkaline inks and will not deteriorate or lose its resilienceover a long period of use. Preferably, the sac is formed of materialwhich is transparent or sufficiently translucent to permit the user toobserve the level of ink therein as hereinafter explained. The sac isadapted to be alternately compressed and released to draw ink into thereservoir for filling the latter in a manner which will be understood asthe description proceeds. The sac I9 may be provided with a plurality ofspaced, longitudinally extending ribs I9a which project inwardly fromthe inner wall thereof and which effectively stiffen the sac to aid itin returning rapidly to its initial shape after compression andsubsequent release of the compressive force.

For the purpose of protecting the sac I9 when the barrel ID has beenremoved for the filling operation (as hereinafter explained) in order toprevent accidental compression of the sac, a guard 29 is provided. Theguard 29 is formed as an elongate hollow member open at its forward endand is telescoped over the sac I9 and the rearward end of the body I5.The open forward end of the guard 29 is secured to an intermediatesection 2I of the body It of slightly greater diameter than the sectionI8. 'While the guard 28 may be secured in any suitable manner, itpreferably is threaded onto the section 2I for convenience in assembly,although, it may if desired, be secured in other ways, as for example,by providing an annular groove (not shown) in the section 2| andspinning the material of the guard into such groove.

The guard is provided with an opening 22 to expose a portion of the sacI9 and to provide access thereto so that the sac may be compressed bythe user. The finger opening 22 preferably is of such longitudinal andcircumferential extent as to permit the sac to be compressed andcollapsed to a substantial extent as hereinafter explained more indetail. The rearward end of the guard 20 is closed as by a button orplug 23 preferably formed of a plastic, and which serves to stiffen andreinforce the end portion of the guard 20 to prevent damage thereto suchas might otherwise result should the 4 end he struck against anotherobject or squeezed tightly by the fingers of the user.

The guard 20 preferably is formed of thinwalled material of suitablerigidity, and preferably a material which is relatively light in weight,and for this purpose preferably aluminumis employed, although othermaterials may be used. The guard 20.;is disposed close to but spacedfrom the sac I9 and in turn is disposed close to but spaced from thebarrel I0 thus permitting the sac I9 to be of relatively large diameterwithout substantially increasing the overall diameter of the pen barrelI0. However, the spaces between the guard and the sac and between theguard and the barrel, respectively, provide dead air spaces which serveto insulate the contents of the sac from external heating ef-- fectssuch as the heat of the hand of the user. In addition, the externalsurface of the guard preferably is polished to provide a reflectingsurface which reflects radiant heat. Accordingly, the contents of thesac are protected against sudden increases in pressure which mightotherwise result from external heating effects and which might tend toforce ink from the pen.

The sac may be compressed manually or by suitable mechanism butpreferably a pressure bar 25 is provided for compressing the sac I 9 toa greater extent than would be conveniently possible were the saccompressed by direct errgagement between fingers of the user. Thepressure bar is so formed that it extends over a substantial portion ofthe length of the sac and hence when the bar is depressed, it compressesa substantial portion of the sac and displaces, a relatively largeamount of air. The pressure bar preferably is formed of resilientmaterial .such as metal and includes a fiat body portion 26 and ahook-shaped end portion 21, which latter engages and is held between theinner walls of the guard and serves both to provide the necessaryresiliency and to hold the pressure bar in position in the guard 20. Toaid in retaining the hooked end, it is provided with spaced small prongs21a which bite into the wall of the guard. The bar 25 is formed with anoffset portion 28 adapted to enter and seat in the finger opening 22 toaid in maintaining the pressure bar in position. In addition, the offsetis of such depth that the upper surface of the portion of the pressurebar which is exposed through the opening 22 is substantially flush withthe adjacent surface of the guard and is in a position for convenientengagement between fingers of the user.

The barrel I9 is formed as a hollow member having an open forward endand is adapted to be telescoped over the guard 20 and a portion of thebody I5 and thereby to inclose the guard 20 and sac IS. The barrel I6 isdetachably connected to the body I5 in order to permit ready removal forthe purpose of providing access to the sac for the filling operation. Tothis end the barrel is threaded at its open end onto a section 30 of thebody I5 of slightly larger diameter than the section 2|. The barrel I0is adapted to be screwed onto the body I5 with its forward limit ofmovement being determined by abutment of the end edge of the barrel I0against a rearwardly facing shoulder 3I provided for this purpose. Therearwardly facing shoulder 3I may be provided conveniently by a portionof the rear face of a clutch ring 32 carried on the body I5 and securelyretained in position thereon. The clutch ring 32 also may serve toretain a slip cap 33 in a. manner '4! adapted to fit in generallysimilar tothat disclosed and claime'din United States Letters Patent No.2,278,901 granted April 7, 1942, to Marlin S. Baker. l The barrel I isprovided with a vent opening 34, preferably located at its rearend,which maintains the airwithin the barrel and externally of the sacat atmospheric pressure. Therefore, no sudden change in the pressure ofthe air which is in' the space within the barrel and surrounding the.sac takes place-when the barrel is moved into "position surrounding theguardor is removed therefrom. Moreover, since the interior of the"barrel is continuoush vented to atmosphere,

there is no possibility of a pressure difierential being establishedbetween the air in the interior of the barrel and the atmosphere whichmight 'eause flooding or starving of the pen when used in writing orleakage during periods of non-use.

' The hollow shell II is secured on the forward section 35 of the body15, which preferably is of less diameter than the section 39.Preferably, the shell I i is threaded onto the section 35 and abuts theclutch ring 32 to maintain it in firm abutment with the forward end ofthe section 38 of maximum diameter, the clutch ring being positioned ona portion of the body member 15 which is of the same diameter as thesection 35 but preferably not threaded. The'shell preferably is ad-'hesively secured on the body 15 by a thermoplastic cement which maybesoftened by heat to permit removal of theshell for repair purposes. Theshell is {to receive the governor l4, and a reduced bore 3'! formed witha chamber 35 adapted extending from the chamber 3B through the forwardend of the shell i l, through which the nib l3 projects.

erally cylindrical body or core 38 having a plu- 'rality oflongitudinally spaced, circumferential fihs' 39 extending radiallytherefrom and defining a plurality of circumferential, longitudinally:spaced capillary spaces or cells 413. The capillary cells 40-are soformed that they progressively increase in width toward the forwardend'of the pen for controlling the flow of ink in a manner explainedmore in detail in said Baker Patent 'No. 2,223,541.

The governor i4 is formed with a shank pQition the bore It forsupporting the overnor M on the body s, with the forward core portionand fins being disposed in the chamberdfi and substantially filling thesame. The governor I4 is positioned in the body l5 by a shoulder 42provided by the rearwardmost fin 43 which fin, as well as theforwardmostfin 44, may be substantially thicker than the remainingintermediate fins 35 for the purpose of increasing their strength." i vFor the purpose of feeding ink from the reservoir II, acapillary'ink'feed duct is provided which takes the form of a fissure 45extending longitudinally of the governor l4 and radially inwardlythroughout the radial extent of the fins 35 and the core 38. The feedduct 45 has a rearward portion 45a which opens at its rear end into thechamber defined by the bore l1 and extends forwardly to the rearwardcells 40, and a forward portion 45b of narrower widthv which extends toshort'of the forward end ofxthe governor Id." The feed duct 45 whichpreferably is disposed in the "bottom portion ofthe governor l4 andintersects the fins 39 and the capillary cells 40 defined thereby.Thus-the capillary cells 4|] are in feeding communication with the feedduct 45 and constitute a capillary overflow space constantly in feedingcommunication with the ink feed duct 45 to receive ink tending to flowthrough the latter in excess of that required for writing purposes. Thethicker fins 43 and serve to maintain the desired spacing of the opposedwalls which define the feed duct 45 but, in order to aid in maintainingthis spacing, aspacing pin 46 may be inserted in a suitable opening ofthe rearward end of the shank 4i.

The governor l4 is formed with an axial bore extending throughout itslength and communicating at its rear end with thechamber defined by the.bore [6 and forming a portion of the ink reservoir. The bore :in thegovernor i4 is formed with a plurality of portions 50, 5|, 52 and 68 ofprogressively decreasing diameters respectively from the forward end ofthe Collector 14 in a rearward direction. The forward bore portion'50provides a socket for the writing nibl3 which preferablyhas acylindrical shank portion53 frictionally fitted. into such socket.'Theshank portion 53 is slotted in its-underside as at 54, and providedwith a notch 55 forwardly for the slot to provide a passage for theentry of air into the reservoir, as hereinafter explained. The nib may,if desired, seat against therear wall of the bore portion 53in order toaccuratelypositlon the nib longitudinally with respect to the associatedpen members. The nib 13 has a forward'tapered writing end portion 56provided with a longitudinal slit 5'! terminating rearwardly in a'pierce58, the nib being of such length that when seated .in the bore portion50 the writing tip projects Such ink feed means includes a feed bar 60associated with the nib I3 and formed with a genorally cylindrical bodyportion 6| frictionally seated in thebore portion 52, and a reducedforward end portion 6-2 extending forwardly through the nib andproviding with the adjacent wall of the bore 31 an air passage extendingthrough the forward end of the shell H and communieating through the nibnotch 55 with the chamber36 in the shell l I. The feed bar-'60 is ofslight- 13; smaller diameter than the interior of the nib 13,- therebyproviding between the nib and feed bar an ,arcuate capillary space 63extending from the rear end of the nib to forwardly of the nib pierce58. This arcuate space 63 communicates with an annular capillary inkspace 64 defined by the bore portion 5| and the adjacent portion of thefeed bar body 3|, which space 64 is in communication with the ink feedduct 45. Thus it will be seen that an ink feed passage is provided whichprovides communication between the reservoir [2 and the nib pierce 58and slit 51. This feed passage functions in a manner-generally similarto that described in Baker Patent No. 2,223,541. However, in order tofurther insure that ink will be delivered by capillary action in the nibBut, an ink feed Sin ll! of capillary Preferably, the bor 31 is slightlyrelieved or recessed above the nib I3, as at 65, to provide an arcuatecapillary space extending over the nib and which receives ink throughthe pierce 58 in order to insure that a quantity of ink is maintained atthe nib slit and the pen, therefore, is always in condition for instantwriting.

Air to replace ink withdrawn from the reservoir in writing is admittedto the ink reservoir I2 by way of the cells 40 and feed duct 45, asexplained in Baker Patent No. 2,223,541, the governor I 4 being providedwith an air channel II (Fig. 4) in its top side, which channel is'ofgreater than capillary width and extends throughout the length of thecollector and in intersection with all of the fins 39 and capillarycells 40, preferably at a point substantially diametrically opposite thefeed duct 45. The air channel II communicates with the chamber 85 andthus with the exterior of the shell I I through the nib notch 55 and thebore 37.

For the purpose of providing for multiple stroke filling of thereservoir, a breather tube 61 of novel construction, arrangement andfunctioning is incorporated in the pen for performing functions enerallysimilar to those of a conventional breather tube. Thus the breather tube61 communicates at its forward end with the feed means and at its rearend with the interior of the reservoir. Thus air is displaced from thereservoir through the breather tube upon compression of the sac, andupon release of the sac a suction is created which draws ink into thesac. Thus upon repeated filling strokes, each consisting of compressionand subsequent release of the sac, ink is drawn into the reservoir insuccessive increments to fill the reservoir.

The breather tube 61 is securely seated in a bore 56 in the feed barbody as by providing slits 15 in the end of the tube, and extendsrearwardly through the bore 68 and into the reservoir I2 and terminatesat its rear end close to the rear end of the sac I9. The bore 66 isconnected through a transverse passage 69 with the annular ink space 64previously described and thus an air discharge path is provided by thebreather tube 61, bore 65, passage 69, annular space 64, arcuate inkspace 63, the forward portion of feed duct 45, capillary cells 40 andair channel ll through which air is displaced from the reservoir I2during the filling operation as hereinafter described. The breather tube61 is disposed axially of the body I5 and the sac I9 and, therefore,when the sac I 9 is compressed and partially collapsed durin the fillingoperation such manipulation does not bend or collapse the breather tube61 and there is therefore no interference with the passage of airthrough the breather tube.

To fill the pen, the barrel I is unscrewed from the body I and is slidrearwardly to disassemble it from the remainder of the pen thereby toexpose the finger opening 22 and render the pressure bar 25 accessibleto the user. The forward end of the pen then is inserted in a supply ofink and the sac I9 repeatedly compressed as by repeated depression andrelease of the pressure bar 25. During the filling operation the pen maybe held by grasping the shell at its rearward portion with one hand andby pressing on the pressure bar with the fingers of the other hand, but,owing to the provision of the rigid guard 20, the pen may be held solelyby one hand and the sac compressed by the fingers of that hand. Uponeach compression of the sac I9, air is displaced from the reservoirthrough the breather-tube 61,

and the air discharge path above described, and thence through the frontend of the shell. At the same time, some air is displaced from .thereservoir through the rear end of the ink feed duct 4-5, capillary cells40, and thence through the front end of the shell. Upon release of thepressure upon the sac, the latter returns to its normal expandedcondition, whereby a suction action is produced which draws ink into thereservoir on a reverse direction along the path through which air wasexpelled during the compression stroke and principally through thebreather tube. It will be understood that where any ink is in the pen atthe beginning of the filling operation, some ink may be expelled withthe air upon the first compression of the sac; also, ink may be expelledwith the air upon subsequent compressions. However, the amount of inkdrawn in during each expansion of the sac is greater than that expelledwith the air during the-previous compression and therefore repeatedcompression and release of the sac I 9 fills the reservoir I2.

It will beunderstood that ink will rise in the reservoir until it standsat a level substantially even with the rear end of the breather tube.Thereafter, the only additional ink which can be drawn into thereservoir is an amount equal to that which is drawn in upon the nextadditional suction stroke. If further strokes are effected, no furtherink will be drawn into the reservoir since upon each such additionalcompression stroke, ink instead of air is forced out of the pen andregardless of the number of such additional strokes, no more ink will bedrawn in upon the expansion of the sac than is expelled during thecompression of the sac. It will be noted, however, that the rear end ofthe breather tube extends to very close to the rear end of the sac sothat the level of the ink at the end of the last effective fillingstroke is very close to the rear end of the sac and the sac, therefore,is substantially filled.

Because the portion of the sac opposite the inner or rear end of thebreather tube is exposed when the barrel is removed and the sac istransparent or translucent, the user may determine by inspection whensufficient ink has been drawn into the reservoir to raise the level ofthe ink to the level of the rearward end of the breather tube 61. Theuser thus is informed that the only further ink which will be drawn intothe reservoir is that which will be drawnin by the next filling strokeand that only one such additional stroke is required to complete thefilling operation. Thereafter the barrel is telescoped over the guard 20and screwed home against the clutch ring 32 and the pen is ready foruse.

In accordance with the present invention, the breather tube is made witha very small internal diameter and correspondingly small internalcross-sectional area. Therefore, only a relatively small quantity of inkstands in the breather tube .at any time and which must be displacedwhen the sac is compressed during the filling operation to expel airfrom the reservoir through the breather tube. Thus, upon eachcompression stroke a relatively small proportion of the combined volumeof ink and air which is expelled through the breather tube consists ofink and a relatively large proportion of such volume is air, with theresult that upon each filling stroke there is only a comparatively smallloss of efiiciency tbecause of the presence of ink in the breather ube.3

except the rearward few cells thereof, to drain back into the reservoirwhen the pen is maintained in point-up position. By reason of thistendency, the governor tends to be cleared of ink when the pen ismaintained in point-up position and has a large proportion of its inkstorage capacity available as stand-by space for receiving ink shouldink tend to flow from the reservoir in excess of that required forwriting. Therefore, unless it is desired to use the pen in writingimmediately after filling it, there is no necessity for clearing thecollector in the course of the filling operation as the collector willtend to clear itself when the pen is held in point-up position as itcustomarily is when carried in the pocket. Where it is desired to writewith the pen immediately after filling,

the overflow ink storage spaces in the governor may be rapidly emptiedof ink at the completion of the filling operation by removing the end ofthe pen from the supply of ink prior to the release of pressure upon thesac I9 after the last compression stroke. That is to say, when the userobserves that the level of the ink has reached the height of the end ofthe breather tube, the sac is compressed an additional time and the penis removed from the supply of ink, whereafter the pressure on the sac isreleased, which draws the ink from the overflow storage spaces into thereservoir. However, where the pen is to be carried in point-up positionbefore being used, it generally is not necessary to perform suchgovernor clearing operation because of the tendency for the governor tobe cleared by drain-back.

In writing, ink finds its way from the reservoir 12 to the nib slit byway of the feed duct 45, the annular ink space 84 and the feed slit 10,as well as the arcuate ink space 63; ink also enters the space 65 abovethe nib as above explained. Air enters the reservoir l2, for permittingink to flow therefrom, by way of the air passage provided between thefeed bar 60 and Wall of the bore 31, the chamber 36, the air channel H,the rearmost capillary cells 39, and the portion of the ink feed duct45a rearwardly of the capillary cells. As will be understood from BakerPatent No. 2,223,541, the capillary cells receive ink which flows fromthe reservoir in excess of that required for writing purposes and fillwith ink, thus blocking the flow of air to the reservoir l2 andpreventing further ink from being withdrawn from the reservoir until thecells are emptied. The cells are emptied either by writing out the inktherefrom or by the establishment of pressure conditions which cause theink to be drawn back into the reservoir from the cells. Because of thegreater capillarity of the rearward cells these remain filled with inkuntil the remaining cells are emptied and thus the entry of air into thereservoir is blocked until substantially all of the cells have beenemptied.

The sac I9 preferably is formed of a material which is relativelynon-wettable (hydrophobic) byinks of the type with'which the pen is tobe used. Therefore there is substantially no tendency for ink to wet andadhere to the walls of the sac when the reservoir is depleted bywriting. In addition the reservoir is formed without crevices or otherformations in which ink would tend to remain. Thus, substantially allofthe ink in the reservoir may be withdrawn when the pen is used inwriting.

It is important that the dimensions of the breather tube and associatedmembers he carefully selected having in mind the above-describedconstruction and arrangement of such elements and the necessaryrelationships therebetween. Excellent results were obtained in onepractical embodiment of a fountain pen embodying our invention, whichpen was generally similar in construction to the pen shown in theaccompanying drawings and comparable in size to fountain pens ofconventional construction, by forming the breather tube 61 (see Fig. 8)with an internal diameter a of approximately 0.036" and an externaldiameter b of approximately 0.046. The vent T2 in the aforesaid breathertube was formed with a diameter c of approximately 0.0 0" although ithas been found that excellent results may be obtained where thisdimension is within the range of from around 0.014 to around 0.026". Inthe aforesaid pen the well "I5 had a diameter d of approximately 0.098",thus providing a wall-to-wall width e of approximately 0.026". Thisdimension may be varied somewhat but must be small enough to providesubstantial turbulence and on the other hand, must be large enough toprevent the formation of a film of ink across the open end of the well.The vent 12 Was located approximately midway of the depth ,f of the wellalthough excellent results may be obtained where the vent is locatedanywhere between such midpoint and a point spaced it" from the open endof the well where the well is formed with the above described diameterand wall-to-wall width. A pen of the foregoing construction and havingits parts dimensioned as above stated may be completely filled withapproximately six filling strokes. Where the vent 12 is formed of thesmaller dimension, the pen may be filled with fewer strokes but wherethe vent is of larger dimension, a greater number of strokes isnecessary.

It will be understood that the foregoing dimensions may be variedsomewhat without departing from our invention so long as therelationships and principles of our invention disclosed herein aresubstantially followed.

Proper feed of ink from the reservoir I2 to the nib slit 51 is insuredby forming the several portions of the capillary ink path between thereservoir and nib slit with such dimensions as will cause ink to bedrawn by capillary action into the several portions of the capillaryfeed path and stand in a continuous column from the reservoir to the nibslit. As an example of the size of the various ink passages constitutingthe feed which have been found suitable for effecting proper flow of theink, the capillary feed duct 45 may have a width of around 0.006" in itsrearward portion 45a and around 0.005" in its forward portion 45?), theannular space 64 may have a radial thickness of around 0.006", thearcuate space 63 may have a radial thickness of around 0.0055", thecapillary space 65 above the nib may have a width or thickness of around0.005", and the feed slit [0 may have a width of around 0.007", althoughthis dimension may be smaller. The nib slit 51 has the smallestcapillary dimension and preferably is from 0.001 to 0.0015" in width toinsure that ink is drawn therein and maintained therein at all times.The capillary cells are of greater cross-sectional dimension and lessercapillarity than the feed duct 45 with which they communicate so thatink will be drawn therefrom and into the feed duct whenever any ink isin the cells during the time the penis 13 in writing so that the cellsare' emptied by writing out.-

From the foregoing, it will be seenthat; the present invention providesamultiple-stroke filling means which is simple in construction andhighly efil'cient in operation. The provision of the very small internaldiameter breather tube decreases the amount of inkwhich is displacedduring the compression stroke, thereby increasing the efficiency offilling. At the same time by reason of the small internal diameter ofthe tube, a large proportion of the ink drawn into the pen in eachsuction stroke enters the reservoir.

The novel proportioning and arrangement of tnevent which is locatedinthe forwardv end of the" breather tube provides the desired so=called"airplane characteristic without materially-decreasing the efficiency ofthe: filling operation. Moreover, the .arrangement is such that while itsubstantially prevents any decrease in the efficiency' of the fillingoperation, on the other hand it does not impair the effectiveness of theventing: function necessary to prevent expulsion of ink from the pen.

By forming the breather tube of silver or its equivalent, a number ofadvantages are obtained in addition to those just above-mentioned. Thetube may be formed of very thin-walled stock and thus even though thevent opening may be made with a small diameter it may nevertheless bemade very short in axial length relative to its diameter. Accordingly,the tendency for a film to form across the vent is substantiallyeliminated. In addition the highly wettable nature of the tube wallsfurther inhibits the formation of such film. Moreover, silver may bereadily fabricated and does not deteriorate over a long period of useand does not contaminate ordinary inks.

We claim:

1. A fountain pen comprising an ink reservoir, a pen nib, feed meansdefining a feed passage connecting the interior of said reservoir andsaid nib, and filling means for displacing air from said reservoirincluding a breather tube fixed relatively to said feed means andcommunicating at its forward end with said feed passage intermediate theends thereof and exteriorly of said reservoir and at its rearward endwith the interior of said reservoir for venting air from said reservoir,said breather tube having a continuously open lateral vent in itsforward portion and intermediate its ends, and means defining arestricted passage opposite said vent providing communication betweensaid vent and the interior of said reservoir, said restricted passagebeing of sufficiently small wall-to-wall width to cause substantialturbulence of air therein upon actuation of said filling means andconsequent displacement of air through said breather tube and therebyprevent substantial flow of air through said vent.

, 2. A fountain pen comprising an ink reservoir, a pen nib, feed meansdefining a feed passage connecting the interior of said reservoir andsaid nib, and filling means for displacing ink from said reservoirincluding a breather tube fixedly v secured relatively to said feedmeans and communicating at its forward end with said feed passageexteriorly of said reservoir and at its rearward end with the interiorof said reservoir, for venting air from said reservoir, said breathertube being provided with a. continuously open lateral vent in itsforward portion providing com-.- munication between the interior of saidtube and said reservoir and having a diameter smaller thanpen-comprising. an ink reservoir,

a pen nib, feed means including a governor hav-.

ing capillary ink storage spaces,v said feed m ans} defining afeedp-assage connectingthe interior of said reservoir andsaid nib andconnected to saidspaces, and a breather tube communicating. at itsforward end with said feed means; exteriorlly or" said reservoir and atits rearward end with the interior of said reservoir forventing, airfromsaid reservoir and having a side vent in its forward portioncommunicating with said reservoir,.said governor and breather tubeforming a well opening? into said reservoir and receiving the.ventedportion of saidbreather tubev to limitthe flow, of air from saidventduring filling, said area-trier tube being formed of silver andproviding surfaces which exhibit; a relatively high degree ofwett'ability with liquid inks.

4. A fountain pen comprising an ink reservoir, a pen nib, feed meansdefining a, feed passage connecting the interior of said reservoir andsaid nib, a breather tube communicating at its forward end with saidfeed eXteriorly of said reservoir and at its rearward end with theinterior of said reservoir, said breather tube having an externaldiameter of around 0.046, an internal diameter of around 0.036", alateral vent in the forward portion of said breather tube of from around0.014 to around 0.026" in diameter, and means defining a restrictedpassage of around 0.026" wall-to-wall width opposite the vented portionof said breather tube and connecting said vent and the interior of saidreservoir.

5. A fountain pen comprising an ink reservoir, a pen nib, feed meansdefining a feed passage connecting the interior of said reservoir andsaid nib and including a feed member in the forward portion of saidreservoir, a breather tube of substantially uniform diameter fixed atits forward end in said feed member and extending rearwardly in saidreservoir with the forward end of said breather tube communicating withsaid feed passage exteriorly of said reservoir and the rear end openinginto said reservoir, said breather tube having a lateral vent adjacentits forward end and said feed member having a bore defining a wellsurrounding the vented portion of said breather tube and providing arestricted passage from said vent to the interior of said reservoir.

6. A fountain pen comprising means defining an ink reservoir andincluding a hollow body member, a pen nib, feed means defining a feedpassage connecting the interior of said reservoir and said nib andincluding a feed member having a shank seated in the forward end of saidhollow body member and formed with a bore communicating with said feedpassage and opening at its rearward end into the interior of saidreservoir, and a breather tube extending into said bore and fixedlyseated therein with the forward end of said tube opening into said boreforwardly of said seat and the rearward end opening into the interior ofsaid reservoir, the portion of said bore rearwardly of said seat beingspaced from the corresponding portion of said breather tube andproviding a restricted passage opening into said reservoir space, saidbreather tube having a lateral vent opening into said restricted passageintermediate the ends thereof.

7. In a fountain pen, means' forming an ink reservoir, an ink feed meanshaving a wall forming a trap or well connected to said reservoir, andfilling mechanism including a silver breather tube with one end passingthrough said trap and connected to said feed means and the other endprojecting toward the rear end of said reservoir, said breather tubebeing thin-walled with a small internal diameter and having a ventopening in that portion of said tube passing through said trap of lessdiameter than the internal diameter of the corresponding portion of saidtube but greater than the wall thickness of the tube.

8. In a fountain pen, a writing nib, means forming an ink reservoir, anink feed means including a well or trap directly connected to saidreservoir and a feed passage connecting said well to said nib, andfilling mechanism including a breather tube of uniform diameter havingone end passing through said trap and connected to said feed meansintermediate the ends of said feed passage and the other end projectingnear the rear end of said reservoir, said breather tube 16 beingthin-walled with a small internal diameter and formed of silver, saidtube also having a small vent opening at a point located in said trapand discharging laterally thereinto.

MARLIN S. BAKER. HARLAN H. ZODTNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 723,726 Perks et al Mar. 24, 19032,375,770 Dahlberg May 15, 1945 2,398,521 Cloutier Apr. 16, 19462,428,863 Wing Oct. 14, 1947 2,521,657 Severy Sept. 5, 1950 FOREIGNPATENTS Number Country Date 3,451 Great Britain Dec. 24, 1862 325,142Italy Mar. 1, 1935

